Air lock



Aug. 12, 1969 J. 5. HERR 3,460,869

AIR LOCK Filed Oct. 9, 1967 2 Sheets-Sheet 1 J. S. HERR Aug. 12, 1969AIR LOCK 2 Sheets-Sheet 2 Filed Oct. 9, 1967 INVENTOR ATTORNEYS UnitedStates Patent O M 3,460,869 AIR LOCK Joseph Stanley Herr, P.0. Box 1416,Wickenburg, Ariz. 85358 Filed Oct. 9, 1967, Ser. No. 673,705 Int. Cl.B65g 53/46, 53/48 US. Cl. 302-50 6 Claims ABSTRACT OF THE DISCLOSUREBACKGROUND OF THE INVENTION This invention relates to air locks for usein air conveying systems, and more particularly to air locks which haveno moving gates, plates, etc., but remain in open condition duringoperation.

Air locks are normally provided in conveying systems where it isdesirable to admit material to be conveyed into a moving stream of air.The purpose of the lock is to allow free flow of material into theairstream, but prevent flow of air into the material container, orhopper. In some instances, material has been dropped from above into theairstream for feeding without using a conventional air lock, but anoccasional blow back will occur which disrupts the feed and creates amajor problem.

SUMMARY OF THE INVENTION The general object of the present invention isto provide an air lock which will assure steady feed without blow back.

A more specific object is to provide such an air lock wherein theprevention of blow back is accomplished without the use of mechanicallyoperated valves.

Another object is the provision of an air lock having an auger type feedfrom the supply container to the airstream, with the auger extendingthrough two adjacent chambers, one a material receiving chamber and theother a surge chamber.

A further object of the invention is to provide an air lock which willinclude a surge chamber to serve as an air cushion by permittingexpansion of reverse flowing air in the material outflow passage andprevent blow back at the material supply outlet.

Other objects of the invention will become apparent from the followingdescription of one practical embodiment thereof, when taken inconjunction with the drawings which accompany, and form part of thisspecification.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a perspective view withthe various components making up the air lock shown separated forclarity;

FIGURE 2 is a perspective view of the air lock in assembled form;

FIGURE 3 is a vertical, longitudinal section through the air lockassembly, taken substantially on the line 33 of FIGURE 2; and

FIGURE 4 is a vertical, transverse section through the 3,460,869Patented Aug. 12, 1969 air lock in the region of the surge chamber, andis taken on the line 4-4 of FIGURE 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The air lock 1 of the presentinvention is adapted to be connected to the outlet 2 of a container orhopper 3. The air lock is designed to transfer material emerging fromthe hopper outlet to an air conveying line 4.

The hopper 3 is shown as having downwardly converging sides 5 formingthe outlet 2. The bottom of the hopper outlet has a peripheral flange 6which is connected by suitable bolts 7 to the inlet end of the air lock1.

The air lock consists essentially of a receiver 8, divided into a basesection 9 and a header section 10, a feed tube 11 and a material pickupchamber 12 which is included in the air conveying line 4. Material(usually granular material) flows from the hopper 3 into the receiver 8and is carried through the base section 9 and feed tube 10 to thematerial pick-up chamber 12 where it is entrained in the airstreamflowing through the line 4.

The base section 9 of the receiver 8 is in the form of and elongatedtrough having its longitudinal sides 13 converging downwardly .to arounded bottom 14. A mounting flange 15 extends around the upper edgesof the side walls and the end walls 16 and 17. A floating auger 18 ispositioned in the bottom of the trough and extends through an opening 19in the wall 17 and along the feed tube 11 which is connected to the wall17 about the opening 19. The shaft 20 of the auger extends through theend wall 16 of the trough and is suitably connected to a drive means 21mounted on the end wall 16. The base section is divided into twocompartments by means of a baflle 22 which extends the full height andwidth of the trough, except for an arcuate opening 23 at the bottom toallow passage of the auger 18. The compartment between the baflle andthe end wall 16 'forms the base of a material chamber, and thecompartment between the baffle and the end wall 17 forms the bottomportion of a surge chamber.

The header section 10 of the receiver also has two sections, a materialchamber 24 and a surge chamber 25. The two chambers are in end to endalignment and have a common dividing wall 26. Material chamber 24 isopen top and bottom, and consists only of four vertical walls 27 withhorizontally extending mounting flanges 28 extending about the upperedges of the Wall for attachment to the flanges 6 of the hopper. Thesurge chamber has three vertical walls 29 and the common dividing wall26 and a top 30. The bottom of the header section of the surge chamberis open for free communication with the surge chamber compartment of thebase section of the receiver. There is a surrounding flange 31 at thebottom of the header section which extends completely around thematerial and surge chambers for mating with the flange 15 to secure thebase and header sections of the receiver together. The two sections canbe joined by bolts 32. When the upper and lower sections are inassembled relation, the common dividing wall 26 of the header section isin vertical alignment with the bafile 22 of the base section so that thetwo :form a continuous dividing wall between the material chamber andthe surge chamber.

The feed tube 11 is simply a length of tubular material forming ahousing about the extended portion of the auger 18, and of suflicientlength to extend from the receiver base. The tube provides a confiningpassage for the material while moving from the base section to thematerial chamber.

Material pick-up chamber 12 actually includes a housing 33, whichencloses the pick-up chamber proper 34, an air inlet duct 35, connectedto the air line 4, and a combined air and material discharge 36,connected to an appropriate conveying line for carrying the material toa desired point of deposit. The housing 33 is approximately triangularin vertical section, with a hon'ozntal bottom 37, a vertical back wall38, generally triangular side walls 39 and an inclined top wall 40. Airinlet duct 35 opens through the back wall 38 near the bottom, and thefeed tube 11 opens through the back wall near the top so that it isabove the air inlet opening, A gravity operated door 41 is hinged at itstop at the top of the opening of the feed tube into the back wall sothat it will close the tube opening when no feed is being fed throughthe tube, or when pressure builds up within the pick-up chamber 34. Ithas been found that a better entrainment of the material with the air,and a more even flow rate of the entrained material is obtained if thedischarge tube 36 inclines slightly from the end of the pick-up chamber.

When the air lock is to be put into operation, the various elements areassembled as described, and the assembled lock is attached to the outletof a container or hopper 3 by bolting the air lock flange 28 to thebottom flange 6 of the hopper. If the hopper has a gate, or other valve,it will be open to allow material to flow out into the material chamber24 and the material compartment of the base section of the air lock. Theair inlet duct 35 will be connected to the air line 4, and the dischargetube will be connected to an appropriate conveying line. Auger drivemeans 21 will be put into operation so that the auger will rotate andfeed material lengthwise of the trough in the base section of thereceiver through the opening at the bottom of the bafiie 22, through thebase of a surg chamber and through the feed tube 11, forcing the door 41to swing open and the material to flow into the pick-up" chamber 34. Ifthe material chamber 24 is kept filled with a steady supply of material,the flow of material into the pick-up chamber 34 will be even. As thematerial falls into chamber 34, it is entrained with the airstreammoving from duct 35 through chamber 34 and out the discharge 36 and willbe entrained with the stream and carried through the discharge and theconveying line. If there is a buildup of material in the conveying line,or for some other reason there is a pressure build-up in the pick-upchamber 34, air may blow back through feed tube 11 into surge chamber25. The build-up of pressure may be so quick that the blow back willoccur before door 41 can close. As the air under pressure emerges fromthe feed tube 11 into chamber 25, it can expand and the pressure will bereduced. Thus, the air is controlled and there is no leakage of the airback into the supply hopper.

In testing the device, the top of the surge chamber was placed at theplane of the base section of the receiver, and it was found thatconsiderable blow back occurred. It was only after the upper section ofthe surge chamber was raised an appreciable extent (for example, four tosix inches) that the lock functioned to practically eliminate blow backinto the hopper. The considerable cushioning area within the uppersection of the surge chamber allows for adequate expansion and pressurereduction so that the blow back does not go into the feed hopper.

While in the above one practical embodiment of the invention has beendisclosed, it will be understood that the particular construction andarrangement of parts shown and described are merely by way of exampleand the invention may take other forms within the scope of the appendedclaims.

I claim:

1. Air lock to feed material from a source of supply to an air conveyingline while preventing air blow back to the source of supply comprising,a chamber to receive material from the source of supply, a pick-upchamber through which the air line will flow, a feed tube extending fromthe chamber to receive material to the pick-up chamber, an anger in thefeed tube to move material from the chamber to receive material to thepick-up chamber, a valve for automatically closing the end of the feedtube at its connection to the pick-up chamber, and a surge chamberthrough which the feed tube passes, the feed tube extending along thebottom of the surge chamber and open along its top to the surge chamberand the surge chamber being of greater depth than the auger to providean expansion space above the auger.

2. Air lock as claimed in claim 1 wherein, the surge chamber is incommunication with the chamber to receive material from the source ofsupply.

3. Air lock as claimed in claim 1 wherein, the chamber to receivematerial and the surge chamber are separated by a common wall, and thecommon wall has an opening at its bottom through which the auger extendsand which provides communication between the surge chamber and thechamber to receive material.

4. Air lock as claimed in claim 3 wherein, there is an air inlet to thepick-up chamber, and the feed tube has an outlet to the pick-up chamberabove the air inlet.

5. Air lock as claimed in claim 4 wherein, the valve at the end of thefeed tube is gravity operated.

6. Air lock as claimed in claim 5 wherein, there is a discharge linefrom the pick-up chamber at an inclined angle to the angle of the airinlet.

References Cited UNITED STATES PATENTS 1,002,556 '9/1911 Bernert 302502,912,768 11/1959 Huston et al. 30236 3,106,428 10/1963 Lenhart 3025OFOREIGN PATENTS 295,233 8/1928 Great Britain.

ANDRES H. NEILSEN, Primary Examiner

